1. Field of the Invention
The present invention relates to a light source system suitable for an endoscope.
2. Description of the Related Art
There has been widely used an endoscope which is configured such that the endoscope having an elongated shape is inserted into a body cavity or the like and observation of a region to be examined and various treatments thereof are performed. In such an endoscope, a light source system is adopted for picking up an image inside the cavity. As the light source system, a light emitting portion such as an LED may be provided at a distal end portion of an insertion portion of the endoscope. Such an LED emits light by drive pulses from a video processor for driving the endoscope.
The video processor is configured to control light emission of the LED by a PWM drive in which a duty ratio of the drive pulses is varied. Since the LED has a characteristic of causing temperature rise with the light emission, measures for heat dissipation are taken in the endoscope such as adopting a ceramic substrate having high heat conductivity, for example, in order to prevent the temperature rise of the LED. Further, in Japanese Patent Laid-Open Publication No. 2007-252516, a technique of controlling a light amount of the LED in accordance with a detection result of a temperature sensor is adopted for heat generation control of the endoscope.
Incidentally, heat dissipation characteristics of the endoscopes are different for each endoscope. Therefore, the video processor is conventionally configured such that the temperature rise of the LED is not greater than a temperature defined for each endoscope by controlling a duty ratio of the drive pulses of the LED in accordance with the heat dissipation characteristic of each endoscope.
As mentioned, the heat dissipation characteristics change in accordance with types of the endoscopes. Therefore, the video processor detects a type of a connected endoscope and determines the duty ratio of the drive pulses based on a detection result.